You want to create a RunnableLambda that takes a string input and returns it reversed. Which code snippet correctly achieves this?

hard📝 Application Q8 of 15

LangChain - Chains and LCEL

You want to create a RunnableLambda that takes a string input and returns it reversed. Which code snippet correctly achieves this?

ARunnableLambda(lambda s: s[::-1])

BRunnableLambda(lambda s: s.upper())

CRunnableLambda(lambda s: s + s)

DRunnableLambda(lambda s: len(s))

Step-by-Step Solution

Solution:

Step 1: Understand string reversal in Python
Using slicing with [::-1] reverses a string.
Step 2: Match lambda to reversal
RunnableLambda(lambda s: s[::-1]) uses lambda s: s[::-1], which reverses the input string.
Final Answer:
RunnableLambda(lambda s: s[::-1]) -> Option A
Quick Check:
String reversal = s[::-1] in lambda [OK]

Quick Trick: Use s[::-1] to reverse strings in lambda [OK]

Common Mistakes:

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